Question:
Do the EC-14 and EC-20 teleconverters work with the kit lenses that came with my Olympus DSLR body?

Answer:
The Olympus E-System of Four Thirds DSLRs is just that – a system. This means that components of the system are, for the most part, compatible with each other. The Zuiko Digital lenses are compatible with all of the E-System DSLR bodies. By the same measure, the EC-14 and EC-20 teleconverters are compatible with all of the E-System Zuiko Digital lenses. Teleconverters can be used with Four Thirds lenses on Olympus PEN Micro Four Thirds cameras when using the MMF-1 (Four Thirds Lens Adapter to Micro Four Thirds Lens Adapter). Of course, using a teleconverter with some lenses may be counterproductive, such as with wide-angle lenses whose purpose is to capture a wide field of view. Because of the teleconverters small size, they are ideal for travel because they can reduce the number of lenses needed to cover a trip.

Teleconverters increase the effective focal length of a lens by magnifying the central portion of the image. The EC-14 magnifies the image by 1.4x and the EC-20 magnifies the image by 2x. The teleconverters cannot be stacked, nor can they be used with the EX-25 Extension Tube.

Because the converters are magnifying the image there will be some loss of light because the light entering the lens is being spread over a larger area by the teleconverter. This is because of the Inverse Square Law. To demonstrate the Inverse Square Law, in a darkened room stand near a wall and point a flashlight at it and then start backing away. You will see that as the circle of light grows wider it also becomes dimmer. It is the same output of light being spread over a wider area, so, in effect, the light becomes thinner (dimmer). It is important to understand this in regard to teleconverters because they make the light reaching the lens and autofocus system dimmer (the EC-14 by 1.4 f-stops and the EC-20 by 2 f-stops). Therefore, the teleconverter changes the effective aperture (f-stop). If a lens such as the 70-300mm Zuiko Digital is extended to 300mm, its maximum f-stop is f5.6. But if it is used with the EC-20, the effective f-stop at maximum aperture of 5.6 (the brightness of the light reaching the sensor and autofocus system) is actually f11. This means that higher ISOs might be required because of the lower light transmission and the image will appear dimmer in the viewfinder. If the light in the shooting environment is too low, the autofocus system may have difficulty getting a focus lock.

The other thing to keep in mind is that because the magnification of the image is increased, the narrower angle of view may make it more difficult to hold the camera steady. If the camera has Image Stabilization, it will take the teleconverter into account when applying the necessary degree of stabilization. When using a teleconverter it is a good idea to use a higher ISO and shoot in the S (Shutter Priority) mode so that higher shutter speeds can be selected to help steady the image. If possible, use a tripod or monopod when shooting with long lenses and teleconverters to steady the camera and lens.